33.gist.js

pragma solidity ^0.5;

contract owned {
    constructor() public { owner = msg.sender; }
    address payable owner;

    modifier onlyOwner {
        require(
            msg.sender == owner,
            "Only owner can call this function."
        );
        _;
    }
}

contract ethForAnswersBounty is owned {
    
    int256 winningAnswer;

    constructor(int256 _winningAnswer) public payable {
        winningAnswer = _winningAnswer;
    }

    function () external payable { }

    function attempt(int256 a, int256 b, int256 c) public returns (bool) {
        int256 result = safeFormula(a, b, c);
        if (winningAnswer == result) {
            payout();
        }
        return false;
    }

    function withdrawEther() public onlyOwner {
        selfdestruct(owner);
    }

    function safeFormula(int256 a, int256 b, int256 c) internal pure returns (int256) {
        assert(a < 7237005577332262213973186563042994240829374041602535252466099000494570602495);
        assert(b < 7237005577332262213973186563042994240829374041602535252466099000494570602495);
        assert(c < 7237005577332262213973186563042994240829374041602535252466099000494570602495);
        assert(a > -7237005577332262213973186563042994240829374041602535252466099000494570602495);
        assert(b > -7237005577332262213973186563042994240829374041602535252466099000494570602495);
        assert(c > -7237005577332262213973186563042994240829374041602535252466099000494570602495);

        return (a*a*a) + (b*b*b) + (c*c*c);
    }

    function payout() internal {
        msg.sender.transfer(address(this).balance);
    }
}